Isaiah Berlin was part of a vital time at Oxford in the 1960s and 1970s when Gilbert Ryle and R.M. Hare expounded linguistic analysis and A.J. Ayer came up from London to preach logical positivism. He was, however, a man apart, concerned not with language but with primary issues: Berlin did not want to fiddle with words while the world burned. In this careful study of his political philosophy, Gray, who is also an Oxford don, explains and analyzes his dominant ideas. As Gray interprets him, Berlin claims that ""human values are objective but irreducibly diverse,"" which means that, for practical purposes, they might as well be relative. People will always be in conflict over rival goods and evils, and reason is inadequate to resolve these conflicts-even if people would listen to reason. Berlin therefore embraces a value pluralism, not a belief in an identifiable, ideal life. This pluralism finally leads him to liberalism because it implies tolerance (never mind the paradox of giving liberalism privileged status in a world of equal values). Gray (Mill on Liberty) astutely guides readers through the complex ideas of an important philosopher, even if his study is somewhat arid at times. But to fault an academic study for being dry is like complaining that sloths are slow-moving: that's just the nature of the beast. (May)